Photographic developer.



UNITED STATES rare.

PHOTOGRAPI-IIG DEVELOPER.

No Drawing.

To all whom it may concern:

Be it known that I, WILLIAM FRAsnn CLAUGHTON KELLY, a subject of the King of Great Britain, residing at 22 l/Vinchendon road, Fulham, in the county of London, England, barrister-at-law, have invented certain new and useful Improvements Relating to Photographic Developers, of which the following is a specification.

This invention relates to the development of photographic plates, films and the like and has for its object the combining in tablet form, of the developing agents proper such as metol or hydroquinone, with the accelerating chemicals such as alkaline salts, as for example, borax, so as to contain the two agents in one and the same tablet. I

For developing say, a quarter plate, one tablet composed of the following ingredients in or about the proportions stated, may be taken as the standard, though the said proportions may be slightly varied according to circumstances such as for compensating for errors of exposure, depending upon the general knowledge of the photographer as to the peculiarities and requirements of the particular plates or films he is using. Metol 2 grains, hydroquinone 4 grains, potassium metabisulfite (powdered) :2; to 1 grain, borax 10 to 20 grains, colloid, such as gum tragacanth, or like adhesive 9. 8., glycerin, or other hygroscopic medium 6. 9. glucose syrup 8. (optional for assisting solubilities). Mix the dry ingredients, add the colloid and glycerin (about two drops of a saturated solution of gum arabic, and 1 drop of glycerin suffice), then add alcohol continuously, and stir to avoid precipitating the colloid, in sufiicient quantity to make the mixture into a paste. Then press the mixture into contact with glass or other molding surface for shaping the paste into tablets if desired, said mixture being allowed to dry therein and when dry, being ready for use. The tablet is dissolved in water for use as a developer.

I wish it to be clearly understood that I do not confine myself strictly to the exact ingredients and proportions set forth above, as it is well known that plates and films vary considerably in their particular requirements Specification of Letters Patent.

Patented Sept. 28, 1969..

Application filed February 9, 1906. Serial No. 300,277.

according to the different lengths of exposure and other peculiarities, and I wish to employ the developer as set forth as a standard, reserving for myself the right to add ingredients or vary the proportions according to requirements. For instance the amount of metol set forth in the foregoing, is found to be insufficient for a half plate, more than double the quantity being required though not three times as much. These variations are well known in photography and can readily be coped with by slightly altering the composition of the developer.

I am aware that various dry or compacted developers only requiring the addition of water have been proposed prepared or used, but these dry compacted developers have not contained borax as a constituent as far as I am aware. The result has been that such developers have been incapable of being preserved as is necessary. The developer pre pared according to the herein described method and containing borax as a constituent is however capable of being preserved practically indefinitely.

I make no universal or general claims to the use of borax in the developer, borax being well known as an addition to liquid developers containing another alkaline salt (see the article Borax in the Dictionary 0 f Photography 8th edition, I-Iazell & Go.) My invention consists in using borax as the accelerating alkali in a solid dry compacted composition, kept or stored ready for solution in water. The borax being a bi-borate and an acid, acts as a preservative of the dry developing constituents in the solid developer tablet. Upon the immersion of the tablet in Water, the borax and water inter-act or re act on each other and the borax hydrolizes into soda and boracic acid and so becomes an accelerator.

The developer, according to the chemical formula above set forth, is the one which I prefer to use in practice. It is a favorite and is the most commercially economical and de sirable and for these and other reasons is found to be the best. The borax, in addition to acting with metol-hydroquinone, also acts with a number of other developers, and equal success may be obtained with these developers, but they are considerably more In testimony whereof I have hereunto set expensive, my hand in presence of two subscribing Wit- What I claim and desire to secure by Let nesses this fifteenth day of January, 1906.

ters Pa ent of the United States is:' WILLIAM FRASER GLAUGHTON KELLY.

A photographic developer consisting of a WVitnesses:

solid dry compacted composition in tablet F. J. RArsoN,

form and containing borax as a preservative. A. H. S'rnvENs. 

